Aldehydes are known to undergo degradation upon storage through polymerization and acetal formation. Thus, often aldehydes must be purified by distillation before use; the presence of degradation products affects not only the concentration of the active aldehyde but also the impurities (sometimes color-forming) often interfere in chemical reactions involving the aldehyde. It is not uncommon in commercial applications where an aldehyde is to be used in the manufacture of fine chemicals to have a specification requiring the product to be 96% pure with less than 1% non-volatiles. It is an object of this invention to stabilize aldehydes against degradation on storage.